1. Field of the Invention
The invention disclosed broadly relates to eyeglasses, and more particularly relates to an improved arrangement for attachment of an auxiliary or “clip-on” pair of lenses to a primary pair of eyeglasses.
2. Description of the Related Art
To alleviate the need to carry multiple pairs of eyeglasses, various types of “clip-on” auxiliary lenses have been introduced. Primarily, this allows clip-on sunglasses to be attached to a pair of primary prescription eyeglasses. The market success of the inventions within this art is often measured by such factors as security of attachment, aesthetic appearance, and comfort to the user.
One type of invention found in the prior art is shown in FIGS. 1-4B. The configuration consists of a set of primary eyeglasses 100 and a separate set of auxiliary lenses 200 containing a number of claws 210. The claws 210 are used to attach or clip the auxiliary lenses 200 to the frame 102 of the primary eyeglasses 100. FIG. 4 illustrates the arrangement of the primary 100 and auxiliary lenses 200 in a decoupled state (FIG. 4A) and a coupled state (FIG. 4B). This arrangement has a number of shortcomings. For one thing, the arrangement is cumbersome and unattractive. Furthermore, the attachment members can often cause scratching of the primary lenses 100 as the auxiliary lenses 200 are taken on and off. This is, especially problematic where the primary lenses 100 and/or the auxiliary lenses 200 are made of plastic which is more prone to scratching as opposed to harder surfaces such as those made from glass.
Yet another class of clip-on inventions (shown in FIGS. 5-9B) uses magnets as the primary means of attaching the auxiliary lenses 600 to the primary eyeglasses 500. Magnets 610 on the auxiliary lenses 600 line up with corresponding magnets 510 on the frames 502 of the primary eyeglasses 500 to form a surface area that is designed to hold the auxiliary lenses 600 in place. FIG. 8 illustrates the arrangement of the primary 500 and auxiliary lenses 600 in a decoupled state (FIG. 8A) and a coupled state (FIG. 8B). FIG. 9 contains a view of the cross-sectional area of intersection of the magnets 610 on the auxiliary lenses 600 with the magnets 510 on the primary eyeglass frames 502.
However, there are several drawbacks associated with the various attachment implementations that use magnets. One drawback is that since magnets are heavy, the magnets required on both the auxiliary lenses 600 and the primary eyeglasses 500 tend to add a substantial amount of weight to the overall assembly. The additional weight results in discomfort to the user. Another drawback is that magnets often cause drawbacks when placed near electronic equipment such as computers or floppy disks. In other words, inadvertently placing either the auxiliary or primary spectacles near such equipment can result in property damage as a result of the magnetic fields that are generated.
A more fundamental drawback with magnetic clip-on lenses 600 concerns the integrity of the attachment to the primary eyeglasses 500. Since most magnetic attachment implementation do not account for dynamic loads in all directions, jarring movements that occur during, for example, exercise will cause the auxiliary lenses 600 to become suddenly detached from the primary spectacles 500. Furthermore, regardless of how secure the attachment mechanism is at the time of manufacture, a number of factors can and often will cause the effectiveness of the magnets to degrade over time.
Additionally, both previous styles of clip-on lenses are separate, detachable pieces that must be attached or detached when going from indoors to outdoors, or vice versa. The person wearing the glasses must scramble to find the auxiliary lenses and reattach them. This process is clumsy and time consuming. Also, the chances of misplacing or losing the auxiliary lenses are increased.
Previous styles of clip-on lenses utilize clip-on frame extensions, such as the clip-on frame extensions 612 illustrated in FIGS. 6 through 9B. These clip-on frame extensions protrude from the clip-on frame device and can tear or scratch materials or surfaces with which they come into contact. In addition, these clip-on frame extensions are often light and fragile in order to reduce the weight and bulk of the clip-on lens device. The often fragile construction of the clip-on frame extensions make them subject to breakage or damage from contact with surfaces or material. For example, clip-on frame extensions often catch on the material of a shirt pocket when the clip-on frame extension is placed into or removed from that pocket, possibly resulting in a tear of the pocket material or the bending or breakage of the clip-on frame extension.
Therefore a need exists to overcome the drawbacks and problems with the prior art as discussed above, and particularly for an improved arrangement for attachment of an auxiliary or “clip-on” pair of lenses to a primary pair of eyeglasses.